Does Stubble Burning Really Cause Delhi's Winter Smog? What The Data Shows

Stubble burning does add to Delhi’s winter smog. On some days, it adds a great deal. The trouble starts when people use a figure from one bad day to explain the whole winter. Traffic still clogs the roads, dust hangs in the air, and smoke from other sources lingers after the farm fires subside.

At O2Cure, we help you understand and manage the air inside your home or workplace. And before you buy an air purifier, it is worth understanding the problem outside your window. Here is what the numbers tell us, and what they mean for the rooms where you spend your day.

An official parliamentary answer dated 10 March 2025 reported that stubble burning contributed an average of 10.6% to Delhi’s PM2.5 between 8 October and 7 December 2024. The maximum contribution during that period was 35%.

Put those numbers side by side. The maximum is much higher than the average. So, if you have seen very different figures in the news, check the dates before deciding that one must be wrong. A peak day and a two-month average answer different questions.

The same answer reported these figures for earlier years:

Read the dates carefully here. Each year covers a slightly different window, and none covers the entire winter. The percentages refer to PM2.5, not the AQI number on your weather app. They are historical figures, not a prediction for winter 2026.

A fire in a field does not send the same amount of smoke towards Delhi every day. The wind matters. So does the weather along the route. Counting fires tells you something useful, but it does not tell you exactly what will reach your neighborhood.

To estimate that, IITM’s Decision Support System brings together information about fires, emissions, weather and chemical changes in the air. It is a model, with uncertainties. No roadside monitor labels every particle as farm smoke or vehicle exhaust.

A 2024 paper describing that system found daily biomass-burning contributions reaching 37% during the peak period in its 2021 post-monsoon analysis. This supports the same broad point: crop smoke can contribute heavily on particular days. It does not make that peak a season-long average.

Because the other sources are still there. Vehicles, industry, waste burning, and dust continue to affect the air. Some pollution comes from within Delhi, and some arrives from surrounding areas. Winter weather can make it harder for that mix to disperse.

On cold, still days, air near the ground can mix less freely with the air above. Pollutants then accumulate in a shallower layer, close to where people live and work. The weather changes how pollution builds up; it does not create the emissions itself.

Reducing farm fires is worth doing. So is reducing the pollution produced closer to home. If the share from stubble burning falls, check the total PM2.5 level too. A smaller share of a badly polluted day is not the same thing as clean air.

Air quality monitoring lets you check what is happening indoors. You may notice levels rise during cooking or change when you open a window. What the monitor cannot do is prove that the particles came from a particular farm fire.

Check what the monitor actually measures. A PM2.5 reading tells you about fine particles in the air. A CO2 reading tells you whether the room is well ventilated. They are measuring completely different things, so one cannot replace the other.

It helps to figure out what you are actually worried about before buying anything. Dust and particles need different equipment than gases or microbes. At Squair, we monitor all three separately through options like the Air Quality Monitor and IAQ-SQUAIR BMS, because treating them as one problem often means solving none of them properly.

An appropriately sized particle-filtering air purifier can reduce airborne particles indoors. It cannot stop outdoor emissions, remove every pollutant, or replace the need to control pollution sources inside the home.

The US Environmental Protection Agency recommends choosing a unit with a clean air delivery rate, or CADR, suitable for the room. When comparing fine-particle performance, check the smoke CADR. A HEPA filter label alone doesn't tell you how quickly the device will clean your space.

Keep the air inlet and outlet clear, follow the filter-replacement schedule, and use a fan setting you can tolerate for sustained operation. A machine that is too noisy to keep running is not a practical fit for the bedroom.

If you are searching for the best air purifier in India, start with those details. The best air cleaner for a small bedroom may be undersized for an open living and dining area.

Our range includes systems for different spaces and installation needs. Options include:

Ask which configuration is being quoted for your space. Check the filters, installation work, and expected particle-removal performance. If a feature is marked optional, get it included in the written specification if you need it. That is easier than discovering the difference after installation.

Whether a listing calls a device an air purifier or an air cleaner purifier, compare the actual specifications. For winter-smog particles, ask for relevant particle-performance evidence rather than relying on a germ-reduction claim.

At O2Cure, we consider the space, its use and the pollutants involved before discussing a solution. A bedroom and a centrally air-conditioned office need different assessments. Our range includes filtration, treatment and monitoring options to support that process.

Explore our air purifier solutions and speak to us about air quality monitoring for your home or workplace. Share the room dimensions, ventilation arrangement, and any readings you already have so we can discuss a suitable approach.

Stubble burning is a real part of Delhi’s winter pollution. The data also makes clear why waiting for farm fires to end is not an indoor air plan. Start by understanding your space and the pollutants you need to address.